1. Field of the Invention
This invention relates to a semiconductor device having a DRAM or the like, and particularly to a semiconductor device formed by stacking a plurality of chip dies.
2. Description of the Related Art
An example of this type of semiconductor devices is a semiconductor device in which a memory module is formed by stacking a plurality of DRAM chips on an IO I/O chip mounted on an interposer board and connecting the DRAM chips to the IO I/O chip by means of through electrodes formed within through silicon vias (Sivia) (see Japanese Laid-Open Patent Publication No. 2004-327474 (Patent Document 1) corresponding to U.S. Pat. No. 7,123,497 (Patent Document 2).
More specifically, according to Patent Document 1, each of the DRAM chips of the memory module has a plurality of vias and through electrodes formed within these vias in order to transfer data signals and data mask signals accompanied by the data signals.
A semiconductor device configured in this manner has advantages that the length of wiring lines connecting a plurality of DRAM chips can be shortened and a DLL, consuming a large amount of current, need be provided only on an IO I/O chip.